Prime Minister Jacinda Ardern has defended the Government's new border-charge policy, saying the Government would expose itself to "high legal risk" if it charged Kiwis returning to New Zealand to live.

The Government will be charging only a small percentage of people for the cost of Covid-19 quarantining and isolation in hotels - essentially people coming here for holidays, or Kiwis leaving and returning, of which there have only been about 1000 so far.

Ardern told Newstalk ZB's Mike Hosking today that the Government had received a range of advice, including legal advice, on what could be challenged.

The Government would not be charging for Kiwis returning home to live permanently.

"If we create a barrier to coming back for good, to someone's legal place of residence, that did carry some high legal risk.

"To charge them would bring a whole range of risks and issues."

She acknowledged a Colmar Brunton poll at the weekend that showed people wanted travellers to be charged, and she said the Government was doing that.

"Ultimately New Zealanders want people to be charged and we are," Ardern told Hosking.

Hosking: But they're not.

Ardern: We have just drawn a distinction on the different circumstances that cause people to travel. So basically if you're here, you're safe, you're in New Zealand and you're making a choice to leave (and return) then yes, you should pay for that. But if you're offshore and you, for no fault of your own, find yourself in circumstances where you need to come home, then you can come home (without being charged). We draw a distinction if you're coming here for a holiday.

Hosking questioned why a loan system could not operate - Ardern replied the Government had reached a balanced situation.

Hosking: But next to no one is [being charged].

Ardern: That is simply not true.

She said about 1000 people had chosen to leave New Zealand out of choice, and return, but she did not have the number of people coming in who could be charged. "Someone who comes home for a short period of time - less than six weeks - you will be charged."

The Government announced the border-charge legislation last week. It intends to be rushed through Parliament in the next two weeks before the House rises ahead of the general election.

The decision will mean a managed isolation and quarantine (MIQ) charge for:

• People who leave New Zealand after the legislation comes into effect.
• People who are visiting New Zealand temporarily.

Travellers required to contribute towards their managed isolation hotel stay will pay $3100 per room and $950 for each extra adult and $475 per child.